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Chapter 25. Glossary
given conditions and is necessary to complete disinfection.
CHOPPER PUMP : A chopper pump is a centrifugal pump, which is equipped with a cutting system
to facilitate chopping/maceration of solids that are present in the pumped liquid. The main advantage
of this type of pump is that it prevents clogging of the pump itself and of the adjacent piping, as all the
solids and stringy materials are macerated by the chopping system. Chopper pumps exist in various
configurations, including submersible and dry–installed design and they are typically equipped with an
electric motor to run the impeller and to provide torque for the chopping system. Due to its high solids
handling capabilities, the chopper pump is often used for pumping sewage, sludge, manure slurries, and
other liquids that contain large or tough solids.
CHROMIUM : A heavy metal commonly regulated by wastewater discharge permits and found in met-
als–related industries and products (including stainless steel). It is typically regulated in two forms – total
chromium and hexavalent chromium. Other heavy metals include – Arsenic (As), Cadmium (Cd), Copper
(Cu), Lead (Pb), Nickel (Ni), and Zinc (Zn).
CITY GATE : CITY GATE STATION – The metering and pressure reducing station where gas is trans-
ferred from a high pressure cross–country transmission line to a low pressure distribution piping system
within a city.
CLAPPER : The hinged closure element of a swing check valve.
CLARIFICATION : Any process or processes used to reduce the concentration of suspended matter in a
liquid, such as quiescent settling or sedimentation. Lagoons provide clarification across the cells and in
quiescent zones in aerated systems, allowing solids to settle into a sludge layer
CLARIFIER : A large, circular or rectangular tank that separates solids from the waste stream by settling
or flotation.
CLEAN IN PLACE (CIP) : Method of cleaning the interior surfaces of pipes, vessels, process equipment,
filters and associated fittings, without disassembly.
CLEAN WATER ACT : Federal legislation passed in 1972 creating the Environmental Protection Agency,
requiring a nationwide system for controlling pollutant discharges and providing for construction and
regulation of publicly owned treatment works.
CLEANOUT : An opening (usually covered or capped) in a wastewater collection system used for insert-
ing tools, rods or snakes while cleaning a pipeline or clearing a stoppage.
CLOSURE ELEMENT : The moving part of a valve, positioned in the flowstream which controls flow
thru the valve. Ball. Gate, Plug, Clapper, Disc, etc., are specific names for closure elements.
CO: precipitation – Term to describe compound used in water treatment to aid precipitation of substances
normally soluble under the conditions employed. Common co–precipitants used in water are iron, alu-
minum, calcium and magnesium.
COAGULANTS : Chemicals that cause very fine particles to clump (floc) together into larger particles.
This makes it easier to separate the solids from the water by settling, skimming, draining or filtering.
COAGULATION : The agglomeration of colloidal or suspended matter brought about by the addition of
some chemical to the liquid, by contact, or by other means. Involves destabilization for repulsive electrical
charges to permit agglomeration of colloid particles in water. This process aids the clarification of water.
COLIFORM : A type of bacteria. The presence of coliform–group bacteria is an indication of possible
pathogenic bacterial contamination. The human intestinal tract is one of the main habitats of coliform bac-